Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=false. The description adds meaningful partial-update context (unmentioned fields are left alone), but it never explains what makes this call destructive, whether changes are reversible, or what permissions are required — gaps that matter for a tool flagged destructive.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences with the core action first, then prerequisite, then the field-selection rule. Nothing is padded, though the phrasing is terse enough that a bit more detail could have been absorbed without cost.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 12-parameter mutation tool with full schema coverage and no output schema, the description covers the essentials: what it does, the ID prerequisite, and partial-update behavior. It falls short only on the consequences of the destructive flag and on failure handling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all 12 parameters including null-to-clear and null-to-unlink semantics. The description's only addition is the partial-update rule and the pointer to list_tasks for the ID, which justifies the baseline rather than exceeding it.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb and resource ('Update an existing task'), which distinguishes it cleanly from list_tasks, create_task, and delete_task. It does not explicitly contrast with near-neighbors like adjust_task_time or update_calendar_event, but the resource is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Use list_tasks to find the task ID first' gives an explicit prerequisite and names the sibling that produces the required input. 'Pass only the fields that need to change' establishes partial-update semantics, though it states no when-not-to-use conditions or error cases.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.